According to the Expressen newspaper, the 29-year-old crashed while training in Bolzano ahead of Tuesday's FIS World Cup competition in Innichen in northern Italy.
"It has been established she has some small bleeding on the brain and she was operated on," Swedish ski cross sporting director Joar Baatelson was quoted as saying.
Holmlund, who is second in the World Cup rankings, finished third at the 2014 Olympics in Sochi.
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(Reporting by Philip O'Connor; Editing by Tony Jimenez)
